Laser in situ keratomileusis (LASIK) is the most popular and successful method of laser eye surgery. The all-laser LASIK technique is our preferred treatment in qualified patients with nearsightedness, farsightedness, or astigmatism. Dr. Hersh has been performing LASIK for over 25 years. In fact, he was the lead author of the clinical trial that led to first FDA approval of the excimer laser for vision correction surgery.

The Optical Principle of LASIK:

LASIK works like a contact lens. However, instead of putting a contact on your eye, the laser removes a thin lenslet of tissue from the surface of the cornea (the clear, front “watch crystal” of the eye). So, rather than putting on a contact lens, in LASIK we are removing what can be thought of as a tissue contact lens. Just like a contact lens, this  focuses your vision to give you clear sight.

How is LASIK Done:

In LASIK, a pancake-like thin flap of the cornea is first prepared with a high speed femtosecond laser called Intralase. Here at the Cornea and Laser Eye Institute – Hersh Vision Group, we use the all-laser technique exclusively. The flap acts to preserve the surface epithelial cells (which are like tiles on a floor) to promote quick healing and improvement in vision; visual recovery is typically overnight (in fact, most patients can drive and return to work the day after LASIK). Next, the Wavelight excimer laser, using a beam of invisible ultraviolet light energy, is used to remove a small amount of tissue (the tissue contact lens) from the corneal surface beneath the flap. The actual laser application takes approximately 1 minute. During the procedure, an eye tracking mechanism assures that all laser spots are placed in the proper location even if your eye inadvertently moves. The specifications of the laser application are determined by the computer of the laser which is pre-programmed with your individualized data as determined during our measurements examination. In the topography-guided Contoura technique, your actual corneal map is also programmed directly into the laser. After corneal reshaping, the LASIK procedure is finished when the corneal flap is repositioned. When the flap is replaced, it lies in the bed of excimer laser removed tissue, causing the surface to change shape with the effect of decreasing nearsightedness, farsightedness, or astigmatism.

The LASIK Procedure:

LASIK procedures are performed here at CLEI in our laser suites. The entire procedure takes approximately 3 hours. During the first hour, we take more tests to confirm our previous measurements. The procedure is performed in two steps and is entirely comfortable. You will be given an eyedrop anesthetic to numb the eye and also a mild sedative to relax you. In the first step to create the LASIK flap, a lid retainer supports your lids to avoid blinking during the procedure. You will be looking up at a microscope light and the actual laser treatment will take around 1 minute. After a short break, the Wavelight laser will be used to reshape the cornea. Dr. Hersh will move the LASIK flap into position and you will be asked to look at a green flashing light in the laser microscope. A video eye tracking mechanism compensates for any eye movements for added safety. The actual laser application will again take around 1 minute. At the end of the LASIK procedure, the LASIK flap is repositioned with fluid.  Eyedrops to avoid infection and control inflammation are applied and will be used for one week.


You are generally comfortable after the LASIK procedure. There may be some stinging for a few hours afterward. Vision usually begins to improve by the next morning. Most people can work the next day; however, you will be seen in the office for an examination on that day.

The Accuracy of LASIK:

In general, more than 95% of patients achieve clear vision like they had with their contact lenses and glasses. In approximately 1 in 20 patients, based on individual healing responses, the entire refractive error may not be corrected or that there might be some overcorrection. If undercorrected, your vision will be clearer without glasses, but less powerful glasses may still be necessary to fine tune to your best vision. For patients who are overcorrected, especially those patients who are somewhat older, reading vision might be difficult without glasses. In these cases where vision is not optimal, we typicallywill consider a touch-up treatment 3 months after the original LASIK procedure to further improve vision.

football vision

Side Effects and Complications of LASIK:

There are 2 generally seen side effects immediately after LASIK. First, your eyes may feel dry. Typically, these sensations are mild and are treated with artificial tear drops and resolve over several weeks.  However, dry eye sensations can last in some patients. Second, you will notice a glare/halo around lights at night early after the procedure. These, too, tend to resolve over the first few days or weeks after the procedure. They can last in a few patients; normally these symptoms can be helped with a retreatment if necessary. Furthermore, older patients, 40 years and older, may require reading glasses after the procedure.

There are also more severe complications that can occur with LASIK, as with all eye surgeries. These will be discussed in depth before your procedure. Rest assured, though, today’s LASIK procedures at the Cornea and Laser Eye Institute are very safe and we do everything to safeguard your outcome from preoperative analysis, to meticulous surgery, to careful postoperative care.


IntralaseWe will discuss the expectations for your personal outcome in particular, and what you may reasonably expect to achieve with your vision. In general, most patients achieved an excellent outcome, although around 5% of patients will undergo a retreatment enhancement procedure to further improve vision if it is not clear after 3 months. In addition, other optical side effects include haloes around lights and glare, especially at night. Typically, these are early symptoms and improve over time. These side effects have been much improved with the new Wavelight LASIK procedure. The other group of relatively rare complications may be secondary to problems with the LASIK surgery itself, subsequent corneal healing, and infection. We will discuss these possibilities in detail.

Although most excimer laser treatments today are done with the LASIK technique, some people may be better off with the surface PRK/LASEK procedure. Our preoperative examination and measurements determine our recommendation of the procedure which would be best in your particular situation.

In general, possible benefits of LASIK as compared with LASEK/PRK:

  • Tissue removal beneath a flap rather than at the surface preserves the surface corneal cells (epithelium) with the advantage of faster visual recovery
  • Postoperative discomfort is reduced
  • Tissue removal beneath a flap may decrease the risk of haze or scarring
  • Retreatments are easier to perform

Some risks of LASIK as compared with LASEK/PRK include:

  • Surgical risks (these are rarer with surgeons experienced in LASIK)
  • Damage to the corneal flap
  • Difficulties with the flap postoperatively

The Cornea and Laser Eye Institute is located in our state-of-the-art facility in Teaneck, New Jersey, an easy commute from Paramus, Morristown, and Princeton, and is the preferred destination for LASIK patients across the bridge in Manhattan, New York City. Our NJ LASIK patients are encouraged to visit our office and have their questions answered personally. Convenient hotel accommodations are available for out-of-state and international patients.

In Depth Articles and Studies:

LASIK Retreatment

In the News:

Should bilateral LASIK be performed sequentially or simultaneously? – January 1, 2000
Re-treatment requires forceps to maintain clear interface, avoid flap damage – February 1, 2000
Tracking trends in LASIK enhancement – March 1, 2000
When two refractive surgeries are better than one – May 1, 2000
At Issue: LASIK enhancement preferences – February 15, 2002
At Issue: Refractive procedures in 2010 – December 15, 2002
At Issue: Lens exchange vs. corneal refractive surgery – June 15, 2004
What are practical applications to civilian refractive surgery from extensive military refractive results, and how could civilian surgeons incorporate those applications into practice? – March 25, 2010

LASIK: A Step-by-Step Surgical Approach (adapted from Dr Hersh’s textbook Ophthalmic Surgical Procedures)

Laser in Situ Keratomileusis (LASIK)


Surgical correction of natural myopia, hyperopia, and astigmatis
Select cases of postsurgical myopia, hyperopia, and astigmatis
Select cases of presbyopia management with a monovision goal


Keratoconus and forme fruste keratoconus
Collagen vascular diseases and inflammatory ocular diseases
?Herpes keratitis
Epithelial basement membrane dystrophy

Preoperative Procedure

  1. Discontinue soft contact lens wear at least 1–2 weeks and rigid contact lens wear 2–4 weeks preoperatively. Confirm stability and regularity of corneal topography.
  2. Patient should not wear eye makeup on day of procedure.
  3. Treat preexisting dry eye and blepharitis. Consider nonpreserved lubricants, lid hygiene, punctual plugs, topical cyclosporine, and oral doxycycline for blepharitis.
  4. Ensure appropriate corneal thickness with ultrasonic pachymeter.

Note: Corneal thickness minus flap thickness minus ablation depth should be > 250 μm to minimize risk of corneal ectasia.


  • Lid speculum
  • Gentian violet marking pen (± 3 mm optical zone marker or Sinskey hook)
  • Cellulose sponges
  • Microkeratome or femtosecond laser
  • LASIK or cyclodialysis spatula
  • LASIK irrigating cannula

Operative Procedure

  1. For lasers requiring pupil dilation, administer tropicamide 1% ± phenylephrine 2.5%. Otherwise, no dilation.
  2. Prep and drape operative eye.
  3. Place lid speculum.
  4. Create LASIK flap.

For mechanical microkeratomes:

i. Choose proper ring size and nominal thickness of microkeratome head, depending on corneal thickness, keratometric steepness, corneal width, and expected ablation depth.

ii. Optional: Premark cornea at anticipated junction of flap and cornea using 3 mm optical zone marker and gentian violet in two or three positions.

iii. Place suction ring, centered on patient’s pupil or geometric center of cornea.

iv. Engage suction.

v. Ensure proper suction pressure with handheld tonometer.

For translational microkeratomes, ensure full engagement of head on ring. For rotational microkeratomes, ensure engagement of head on vertical post.

vii. Ensure there are no impediments to the translational path of the microkeratome head.

viii.Engage foot pedal for complete microkeratome pass.

ix. Reverse microkeratome pass.

x. Discontinue suction.

xi. Remove microkeratome assembly from cornea.

For femtosecond laser flap creation:

i. Choose flap diameter and thickness, hinge width, and side cut angle. Typical settings:

(a) Diameter: 8.5–9 mm.

(b) Flap thickness: 100–120 μm.

(c) Hinge width: 45–55 degrees.

(d) Side cut angle: 70 degrees.

ii. Confirm energy settings.

iii. Choose hinge placement (superior, nasal, temporal).

iv. Optional: Mark cornea over pupil center with 3 mm OZ marker or Sinskey hook impregnated with gentian violet.

v. Place suction ring centered on pupil.

Engage suction.

vii. Dock applanation cone into suction ring.

I. Maintain centration.

II. Ensure size of meniscus is larger than flap width.

viii.Perform laser application.

5. Lift LASIK flap with LASIK or cyclodialysis spatula (Fig. 22.1). For laser flap procedures, use cyclodialysis spatula to break flap adhesions.

a. Enter edge of dissection with spatula near hinge.

b. Release flap edge using edge of spatula or Sinsky hook starting from hinge and proceeding around edge for ~180–270 degrees.

c. Advance spatula across cornea at hinge.

d. Sweep approximately one third to one half of cornea from hinge to opposite end of flap.

e. Repeat spatula entry at hinge and sweep gently to break all lamellar and edge adhesions.

6. Retract flap and place on moistened section of cellulose sponge (Fig. 22.2).

7. Optional:

a. Perform intraocular pachymetry to ensure postoperative corneal bed will be > 250 μm to minimize risk of corneal ectasia.

b. May perform “bubble” pachymetry before lifting flap in laser-flap procedures.

Laser Ablation

8. Gently wipe bed with cellulose sponge to remove residual fluids.

9. Engage laser eye tracker and align laser as necessary

a. Alignment technique varies with laser platform.

b. Center over pupil.

10. Encourage patient to maintain gaze at fixation target.

11. Perform laser ablation with laser focused at corneal plane.

12. Replace flap.

a. Use irrigating cannula or spatula.

b. Float flap into proper position usdest irrigation.

c. Align gutter with preplaced gentian violet positioning marks (Fig. 22.3)

d. Ensure there are no flap sriae or interface debris. Irrigate, reposition, or gently

smooth with spatula as necessary.

13. Administer corticosteroid and antibiotic drops.

14. Administer nonpreserved lubricant.

15. Remove lid speculum carefully so as not to disrupt flap position.

Postoperative Procedure

  1. Place protective shields or goggles until patient is examined on postoperative day 1. Continue eye protection for 2 additional nights when sleeping.
  2. Corticosteroid drops 4 times per day for 1 week.
  3. Topical antibiotic 4 times per day for 1 week.
  4. Nonpreserved lubricants as needed.
  5. Continue dry eye/blepharitis management as needed.
  6. Explain postoperative management to patient.

Follow-up Schedule

  1. Postoperative day 1: General examination with attention to flap striae. If significant striae are present, reposition flap in operating room.
  2. Postoperative week 1: General examination with attention to flap, assess for any infection of diffuse lamellar keratitis
  3. Month 1
  4. Month 3 (full exam to assess status and consider retreatment if necessary)
  5. Months 6, 12 as necessary


Intraoperative Flap Problems

  1. Short flap
  2. Thin flap
  3. Buttonhole in flap
  4. Free flap

Early Postoperative Complications

  1. Slipped flap or flap macrostriae
  2. Epithelial defects or sloughing
  3. Iris tuck by the intraocular lens

Intermediate-Term Complications

  1. Diffuse lamellar keratitis (DLK)
  2. Microbial keratitis
  3. Microstriae
  4. Epithelial ingrowth

Late-Term Complications

  1. Over- and undercorrections
  2. Induced astigmatism
  3. Induced topography irregularities
  4. Corneal ectasia and keratoconus


Thank you so much Doc! When I first came to you I was 20/50 now I'm 20/10. I'm ready to have a great year!

Randy Foye
Pro Athlete, Utah Jazz #8

My experience at The Cornea and Laser Eye Institute has been amazing. All of the staff have been helpful and courteous...

Phd Student, MMA fighter

Dr. Hersh and his staff were excellent. I was comfortable from the time I walked in until the time I left after the procedure.

Luke Petitgout
Pro Athlete, New York Giants Football